Alternator help

[colin peck]

Hi Guys,
Just got my '56 Crown Vic back from the shop having the front suspension totally rebuilt, after which it spent a day at the alignment shop making sure it all runs straight and true. Drives great an am really pleased.

Went to move it this morning and noticed the ignition/generator light failed to illuminate, yet the engine started and ran fine. Presumably there's now no charge going to the battery...

It was previously fitted with a Transpro D1701 alternator and after checking contacts etc I found that the white plug (as seen in the attached image) does not have a connection. The terminal is bright and clean, so I know that a wire is missing but after taking the battery out, and the right front wheel off (to check) there is no sign of any random wire??? Maybe one of the shop mechanics pulled the connection off by accident, but it about 15 miles from my house and I don't want to risk driving back there with no charge.

The alternator has one wire connected to the starter solenoid. I've tried to find a wiring diagram for the alternator online, but can only pull up generic diagrams. These, however, suggest that unconnected terminal should be connected to the + side of the battery.

Any thoughts or suggestion, before I risk shorting everything out.

 

[dmsfrr]

Put a voltmeter on the battery terminals when the engine is off. It should read about 12.5 to 13-ish volts.
Then start the engine and with it running at a slightly fast idle measure the voltage on the battery terminals again. If it's higher, around 14+ volts, the system is charging.
Usually the 'Gen' light comes on when you first turn the key on, as a bulb test, then goes out when the engine is running, since the system will be charging.
You may actually have a charging problem... or just a burned out (or disconnected) bulb.
.

 

[JimNNN]

Usually the 'Gen' light comes on when you first turn the key on, as a bulb test, then goes out when the engine is running. You may actually have a charging problem... or just a burned out (or disconnected) bulb.

Yes the OP wasn't clear on that point. I DON'T want a glowing red gen light when the car is running.



If he means the bulb isn't coming on when the key is turned but before the car is started, then he needs to be focusing on the bulb or connection and not worry about the charging system...yet.



Have no idea how the 12 volt '56 gen light works, but on my 6 volt '54, the gen light is hooked up to the voltage regulator, but I can't remember which terminal. When the charging contact is opened the light will go off, as I recall. Regardless, my connection is irrelevant because the shop manual for a '56 has the correct connection...but it's been switched to an aftermarket alternator. Maybe the instructions for that unit are online.



BTW, it's very plausible that the wire to the regulator or whereever was inadvertently pulled off while they were doing front end work.

 

[Jwawhite]

dmsffr. Has got the ticket to determine voltage.